As to the Navy not taking his reporting seriously.....gee...now that is a surprise ain't it!
The fact no one in a position of authority....or a position that could make, cause, or effect change gave him any credence is the indication of how valid his observations are.
Fine young Men and Women have been dying in helicopters since they came about....and shall continue to do so as it is a complicated and complex collection of parts to begin with....then one has to properly put them together and learn to safely operate them in very demanding circumstances.
The US Navy and Marine Corps do not have a monopoly on that by any means.
The RAF and Royal Navy are not immune from this either.